FDC37B78X SMSC Corporation, FDC37B78X Datasheet - Page 19

• Manufacturer Part Number: FDC37B78X
• Description: Enhanced Super I/O Controller with ACPI Support/ Real Time Clock and Consumer IR
• Manufacturer: SMSC Corporation

STATUS REGISTER B (SRB)
Address 3F1 READ ONLY
This register is read-only and monitors the state of several disk interface pins in PS/2 and Model 30
modes. The SRB can be accessed at any time when in PS/2 mode. In the PC/AT mode the data bus
pins D0 - D7 are held in a high impedance state for a read of address 3F1.
PS/2 Mode
BIT 0 MOTOR ENABLE 0
Active high status of the MTR0 disk interface
output pin. This bit is low after a hardware reset
and unaffected by a software reset.
BIT 1 MOTOR ENABLE 1
Active high status of the MTR1 disk interface
output pin. This bit is low after a hardware reset
and unaffected by a software reset.
BIT 2 WRITE GATE
Active high status of the WGATE disk interface
output.
BIT 3 READ DATA TOGGLE
Every inactive edge of the RDATA input causes
this bit to change state.
RESET
COND.
7
1
1
6
1
1
DRIVE
SEL0
5
0
TOGGLE
WDATA
4
0
19
BIT 4 WRITE DATA TOGGLE
Every inactive edge of the WDATA input causes
this bit to change state.
BIT 5 DRIVE SELECT 0
Reflects the status of the Drive Select 0 bit of
the DOR (address 3F2 bit 0). This bit is cleared
after a hardware reset and it is unaffected by a
software reset.
BIT 6 RESERVED
Always read as a logic "1".
BIT 7 RESERVED
Always read as a logic "1".
TOGGLE
RDATA
3
0
WGATE
2
0
MOT
EN1
1
0
MOT
EN0
0
0